Wild fish vs. farmed fish

Time for a battle royal, a smackdown over who's the real sustainable source of fish, fishing or fish farms.

Right now, fishing has the moral high ground with stories on contamination in farmed fish and ocean harm from fish farms. But aquaculture is making a strong push with economic clout and improving technology, and the acccurate pitch that the world needs farmed fish.

Now a fish farming business is making a run at the moral high ground of sustainability, with a striking new argument that actually rings true to me.

Does fishing really have less impact on oceans than fish farming? Many ocean people make this claim, often in a blanket way as though fish farming is always bad. From my perspective, badly-managed fishing is clearly worse than a good fish farm. And, I think for good fish farms and good fishing it's not clear which is worse for the ocean.

One point rarely raised is that fish caught in the wild are eating a lot of forage and may have more ecological impact on forage fish than capture for fish farming. I know some will say "that's ok, because it's natural impact" but that argument doesn't sway me.

Kona Blue, purveyors of sustainable farmed fish, want you to think about these questions. According to The Earth Times, they've just released a new report that includes some provocative claims about how farmed fish are often much more sustainable than wild fish. I'm trying to track down the original report for you, and I'll offer more when I've had a chance to dig in. Stay tuned, this issue is going to grow in importance.

Here's Kona Blue, quoted in The Earth Times.

“If we examine the true environmental cost of wild-caught predatory fish -- such as swordfish or tuna -- we find sustainably maricultured fish have some 60 times less impact on fish stocks at the base of the food chain, such as sardines and anchovies,” said Neil Anthony Sims, President of Kona Blue. The leading offshore mariculture operation in the U.S., Kona Blue raises sashimi-grade Kona Kampachi®, a Hawaiian yellowtail, off the coast of Hawaii.

“What would ocean-conscious consumers rather have on their plates?” asked Sims. “One pound of Kona Kampachi®, or one sixtieth of a pound of tuna? The impact on the oceans is about the same.”

Sims bases this estimate on three primary considerations. First, aquaculture is continually moving towards sustainable substitutes in farmed fish diets to lessen reliance on fishmeal and fish oil. Kona Blue’s current feed formulation includes only 35% fishmeal/fish oil from wild baitfish, of which approximately 3% is from capture fishery by-product. Contrary to outdated ratios of 5:1 or higher quoted by some environmental groups, the current ratio of “wild fish in to farmed fish out” has fallen to approximately 1.5:1 (1.5 lbs. of anchovies producing 1 lb. of sashimi-grade farmed fish).

By contrast, wild fish are subject to the laws of trophic transfer, where only 10% of their prey’s food value is transferred up each step of the food chain. “If a tuna eats a mackerel that earlier ate an anchovy, then there are two trophic steps, compounding the costs,” said Sims. “A tuna may therefore need to eat the equivalent of 100 pounds of baitfish to increase its weight by one pound.” As the fishmeal/fish oil for farmed fish feed involves only one efficient step, trophic transfer loss is minimized.

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